nacre

mother of pearl

An organic-inorganic composite material produced by some mollusks as an inner shell layer; it is also what makes up pearls. It is very strong, resilient, and iridescent. Nacre is found in some ancient lineages of bivalve gastropod and cephalopod. The inner layer in the great majority of mollusk shells is porcellaneous, not nacreous, frequently resulting in a non-iridescent shine or less commonly in non-nacreous iridescence such as flame structure (e.g. conch pearl). Pearls and the inside layer of pearl oyster and freshwater pearl mussel shells are made of nacre. Many other families of mollusk also have a nacreous inner shell layer, including marine gastropods such as the Haliotidae, the Trochidae and the Turbinidae. Nacre is composed of hexagonal platelets of aragonite (a form of calcium carbonate) 10-20 µm wide and 0.5 µm thick arranged in a continuous parallel lamina. These layers are separated by sheets of organic matrix composed of elastic biopolymers (such as chitin, lustrin and silk-like proteins)[WP].

Type Organ
Structure parente organism substance
Nom latin mother of pearl

Questions fréquentes

What is nacre?
Nacre, commonly known as mother-of-pearl, is the iridescent organic-inorganic composite material produced by certain mollusks that lines the inner surface of their shells. It is also the primary component of natural pearls.
What is the chemical composition of nacre?
Nacre is composed of microscopic platelets of aragonite (a calcium carbonate polymorph, CaCO3) arranged in alternating layers with thin sheets of organic biopolymers (mainly proteins and polysaccharides). The ordered lamellar arrangement gives nacre its remarkable mechanical properties.
Why is nacre so strong despite being made of brittle material?
Nacre's exceptional strength and fracture resistance arise from its 'brick and mortar' microarchitecture: the aragonite platelets act as bricks held together by the organic matrix mortar. Cracks must navigate around the platelets, absorbing enormous amounts of energy before propagation.
What causes the iridescent appearance of nacre?
The iridescence (play of color) of nacre results from light interference and diffraction effects. The thickness of the aragonite layers (approximately 200–500 nm) is comparable to the wavelengths of visible light, causing different wavelengths to be reflected constructively depending on the viewing angle.
In what animals is nacre found?
Nacre is produced by certain bivalve mollusks (pearl oysters, freshwater mussels, abalone), some gastropods, and nautiloids. Not all mollusks produce nacre—it is specific to those with the genetic and cellular machinery to deposit ordered aragonite layers.

Structures associées

mucus body coating mucous body coating mucus cocoon mucous cocoon Mullerian duct ductus paramesonephricus multi cell part structure cell part cluster multicellular anatomical structure multicellular structure multilaminar epithelium laminated epithelium multi-tissue structure multi-tissue structures multi-unit eye

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Data sources: Terminologia Anatomica, Foundational Model of Anatomy, Wikidata.